Method for manufacturing an aerogel-containing composite and composite produced by that method

ABSTRACT

The invention relates to a method for manufacturing an insulating composite containing mineral fibers, aerogel and binder. This method implies the step of suspending the fiber webs and aerosol in an air flow thereby disentangling the fiber webs and mixing fibers, aerosol and eventually binder homogeneously. The apparatus described combines spinning of the fibers, collecting them as webs, disentangling the fiber webs in suspended air, mixing the fibers with aerogel and cement as well as pressing and curing the mixture to a consolidated product of density 150 to 800 kg/m 3 .

FIELD OF THE INVENTION

The invention relates to a method for manufacturing anaerogel-containing composite and the novel aerogel-containing compositeproduced by that method. The invention also relates to apparatussuitable for carrying out the method of the invention.

BACKGROUND OF THE INVENTION

It has previously been attempted to provide an aerogel-containingcomposite for use as an insulating material. For example WO 97/10187 A1relates to a composite aerogel material and a method for manufacturingan aerogel containing composite comprising the steps of providing fibersin an amount of from 0.1 to 40%-vol., providing an aerogel particulatematerial having an average particle diameter smaller than 0.5 mm in anamount of from 5 to 97%-vol., providing a resin binder, mixing theingredients, and consolidating the ingredients by subjecting thematerial to hot pressing. This prior art document relates primarily toaerogel composites for electronic purposes taking advantage of lowconductivity and low dielectric constant of aerogel. For this particularapplication thin layers are needed, such as 0.01 to 2 mm, which meansthat the size of the aerogel particles will influence the mechanicalproperties of the composite, so the focus of this prior art is to useaerogel particulate material having a very small diameter. Noinformation is provided in the specification regarding the method usedto mix the various components of the composite and how this affects theproperties of the finished product. In particular, the skilled man isunable to achieve a homogeneous composite based on the informationdisclosed.

Another example can be found in US 2003/0077438 A1, which also relatesto a composite aerogel material and a method for providing a compositeaerogel material comprising the steps of providing fibers in an amountof from 0.1 to 40%-vol., providing an aerogel particulate materialhaving an average particle diameter of at least 0.5 mm in an amount offrom 5 to 97%-vol., providing a resin binder, mixing the ingredients,and consolidating the ingredients by subjecting the material to hotpressing. The resulting composite is alleged to possess good thermalinsulation and good insulation against airborne sound. However, thisdocument provides no information regarding the method used to mix thecomponents of the composite and how this affects the properties of thecomposite. It does not teach the skilled person how to achieve a highlevel of homogeneity in the composite.

One of the main problems of previous aerogel containing composites andmethods for manufacturing thereof is lack of cohesion and mechanicalstrength of the composites.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide anaerogel-containing composite having high mechanical strength and amethod for manufacturing the composite.

According to the invention this object is achieved with a method formanufacturing an aerogel-containing composite, said method comprisingthe steps of:

providing mineral fibers in an amount of from 24 to 80 wt % of the totalweight of starting materials,

providing an aerogel particulate material in an amount of from 10 to 75wt % of the total weight of starting materials,

providing a binder in an amount of from 1 to 30 wt % of the total weightof starting materials,

suspending the fibers in a primary air flow and suspending the aerogelparticulate material in the primary air flow, thereby mixing thesuspended aerogel particulate material with the suspended fibers,

mixing the binder with the mineral fibers and/or aerogel particulatematerial before, during or after mixing of the fibers with the aerogelparticulate material,

collecting the mixture of mineral fibers, aerogel particulate materialand binder and pressing and curing the mixture to provide a consolidatedcomposite with a density of from 120 kg/m³ to 800 kg/m³, such as from150 kg/m³ to 800 kg/m³.

This method can be used to produce a novel aerogel-containing composite.

One particular novel composite comprises:

fibers in an amount of from 24 to 80 wt % of the total weight ofstarting materials, aerogel particulate material in an amount of from 10to 75 wt % of the total weight of starting materials,

binder in an amount of from 1 to 30 wt % of the total weight of startingmaterials, wherein the composite is substantially homogeneous and iscured and pressed to a density between 120 kg/m³ and 800 kg/m³, such asbetween 150 kg/m³ and 800 kg/m³.

The percentages mentioned are based on dry weight of starting materials.

With the method according to the invention as defined above a veryversatile and cost efficient method for manufacturing an aerogelcontaining composite is achieved. A wide range of properties in terms ofe.g. mechanical strength, thermal insulation capability etc can beproduced by altering the quantity of each component. This means thatwith the same method a variety of different composites can be made thatare tailor-made for specific purposes.

Furthermore, it has been found that mixing the fibers and the aerogelparticulate material as a suspension in an air flow provides asurprisingly homogeneous composite, especially considering theconsiderable differences in the aerodynamic properties of thesematerials. This high level of homogeneity in the composite resultsgenerally in an increased level of mechanical strength relative to thecomposites of the prior art for a given combination of quantities of thecomponents. The increased homogeneity of the product also has otheradvantages such as aesthetic appeal and consistency of propertiesthroughout a single product.

We believe that as a result of mixing the aerogel particulate materialwith the mineral fibers when suspended in an air flow, as in the presentinvention, the aerogel particulate material is allowed to penetrate intothe tufts of fibers that are present. In contrast, when the mixingprocess involves physical contact of, for example, a stirrer with thefibers, the fibers tend to form compact balls, which the aerogelparticulate material cannot penetrate easily. The result of this can bethat, in cases where the mixing process involves physical contact, thefinal product contains areas where the aerogel and the fibers arevisibly separated in distinct zones.

It has also been found that the composites of the present invention as aresult of their homogeneity can be machinable in a similar way to wood.By “machinable”, it should be understood that the composite can bemachined in ordinary wood forming machinery, such as saws and shapingmachines, e.g., grooving machines, surface milling cutters etc. Theproducts produced by the method of the invention have a variety of uses,predominantly as building elements. In particular, the products can bein the form of panels. In general, the products are used in applicationswhere mechanical stability and an even surface finish as well asinsulating properties are important. In some applications, the panelscan be used as acoustically absorbing ceiling or wall panels. In otherapplications, the panels can be used as insulating outer cladding forbuildings.

Preferably, the composite is in the form of a panel. Preferably, thethickness of the panel is from 4 to 25 mm. In some embodiments,especially where the panel is used as cladding on a building, thethickness of the panel is preferably from 4 to 12 mm, more preferablyfrom 5 to 10 mm and most preferably from 6 to 8 mm. In alternativeembodiments, especially where the panel is used as an insulation panelfor a wall of a ceiling, the thickness of the panel is preferably from12 to 25 mm, more preferably from 15 to 23 mm and most preferably from18 to 21 mm.

“Aerogel” when used in the broader sense, means a gel with air as thedispersion medium. Within that broad description, however, exist threetypes of aerogel, which are classified according to the conditions underwhich they have been dried.

These materials are known to have excellent insulating properties owingto their very high surface areas, and high porosity. They aremanufactured by gelling a flowable sol-gel solution and then removingthe liquid from the gel in a manner that does not destroy the pores ofthe gel.

Where a wet gel is dried at above the critical point of the liquid,there is no capillary pressure and therefore relatively little shrinkageas the liquid is removed. The product of such a process is very highlyporous and is known as an aerogel, the term being used in the narrowsense. On the other hand, if the gel is dried by evaporation undersub-critical conditions, the resulting product is a xerogel. In theproduction of a xerogel, the material usually retains a very highporosity and a large surface area in combination with a very small poresize. In the wider sense of the word, aerogels also encompass dried gelproducts, which have been dried in a freeze-drying process. Theseproducts are generally called cryogels.

The term “aerogel” in its broader sense of “gel having air as thedispersion medium” encompasses each of aerogels in the narrower sense,xerogels and cryogels. As used herein, the term “aerogel” denotesaerogels in the broader sense of a gel having air as the dispersionmedium.

Preferably, the aerogel used in the present invention has been driedunder supercritical conditions, i.e., an aerogel “in the narrow sense”as described above.

The aerogel used in the present invention is in particulate form. In apreferred embodiment, the particles of aerogel will have an averagediameter of from 0.2 to 5 mm. More preferably, the average diameter ofthe particles in the aerogel particulate material will be from 0.3 to 4mm. and most preferably the average diameter of particles in the aerogelparticulate material will be from 0.7 to 1.2 mm. These particle sizesare measured as weight averages and refer to the particle size of thestarting material, rather than that present in the final composite.

During the method of the invention, in some embodiments, the averageparticle size of the aerogel can be reduced, as a result of the methodsteps used.

The aerogel particulate material can be any type of aerogel. Inparticular, the aerogel can be organic or inorganic. In view of theirfire-resistant properties, inorganic aerogels are usually preferred.Organic aerogels include carbon aerogels and polymeric aerogels. Organicaerogels generally have a lower price and better insulation properties.Preferred inorganic aerogels are based on metal oxides. Particularly,preferred materials are silica, carbides and alumina. Silica aerogels,such as “Nanogel® Fine Particle Aerogel” from Cabot International aremost preferred.

The aerogel particulate materials have a low density, typically from0.01 g/cm³ to 0.3 g/cm³. The thermal conductivity of the aerogelparticulate material is preferably from 5 to 20 mW/mK, more preferablyfrom 7 to 16 mW/mK and most preferably from 9 to 12 mW/mK.

The precise quantity of mineral fibers used in the method and present inthe composite of the invention is chosen so as to maintain appropriatestrength and appropriate thermal insulation value, depending on theappropriate application, as a high quantity of fibers increases thestrength of the composite, but decreases the thermal insulation value.This means that the lower limit of 24 wt % results in a composite havingunusually good thermal insulation properties, and only adequatestrength, which may be advantageous for some composites, where thestrength is less important. If strength of the composite is particularlyimportant the amount of fibers can be increased to the upper limit of 80wt %, but this will result in only adequate thermal insulationproperties. For a majority of applications, a suitable composition willinclude a fiber amount of from 30 to 70 wt % or from 40 to 70 wt %. Mostusually, a suitable quantity of fibers will be from 50 to 60 wt %.

Similarly, the amount of aerogel particulate material used is chosen inorder to provide both appropriate strength and thermal insulation value,as a high amount of aerogel particulate material decreases the strengthof the composite, but increases the thermal insulation value. This meansthat the lower limit of 10 wt % aerogel particulate material results ina composite having excellent strength, but mediocre thermal insulationproperties, which may be advantageous for some composites, where thestrength is very important. If thermal insulation value of the compositeis important, the amount of aerogel particulate material can beincreased to the upper limit of 75 wt %, but this will result inmediocre strength. For a majority of applications, a suitablecomposition will include an aerogel particulate material amount of from30 to 60 wt %, from 35 to 55 wt % or most typically from 40 to 50 wt %.

The amount of binder is also chosen on the basis of desired strength andcost, plus properties such as reaction to fire and thermal insulationvalue. The lower limit of 1 wt % results in a composite with a lowerstrength, which is however adequate for some applications, and has thebenefit of relatively low cost and potential for good thermal insulationproperties. In applications where a high mechanical strength is needed,a higher amount of binder should be used, such as up to the high limitof 30 wt %, but this will increase the cost of the resulting product andfurther the reaction to fire will often be less favorable, depending onthe choice of binder.

It is believed that the binder does not connect to the aerogelparticles. Instead, only the fibers are connected by the binder, and theaerogel particles are believed to be entrapped between the fibers in thecomposite after curing of the binder. Advantages of the indirect,mechanical retention of aerogel particles include that the mechanicalproperties of the resulting composite will not be compromised by therelatively brittle aerogel particles. Further, the insulation propertiesof the aerogel particles will not be compromised by the binder, whichwould be the case if binder connected to the surface of the aerogelparticles. Furthermore, the small aerogel particles would consume a lotof binder due to the large surface area. The connection of fibers toother fibers by the binder, but not of fibers with aerogel isparticularly prevalent in embodiments in which the aerogel particles arehydrophobic and highly non-polar, and in which the binder used is apolar binder such as novolac dry binder. In these embodimentsespecially, the binder will bind to the surfaces of the fibers, but willnot bind to the surface of the aerogel particulate material.

A further advantage of the aerogel particles being entrapped between thefibers in the composite is that this makes it possible to glue togethercomposite boards. Pure aerogel boards are very difficult to gluetogether because of the hydrophobic and highly non-polar nature of theaerogel. By having the aerogel particles entrapped in a fiber structure,it is possible to glue together composite boards, which is believed tobe due to the glue bond to the fiber structure.

The mineral fibers (also known as man-made vitreous fibers or MMVF) usedaccording to the present invention could be any mineral fibers,including glass fibers, ceramic fibers or stone fibers, but preferably,stone fibers are used. Stone wool fibers generally have a content ofiron oxide at least 3% and alkaline earth metals (calcium oxide andmagnesium oxide) from 10 to 40%, along with the other usual oxideconstituents of mineral wool. These are silica; alumina; alkali metals(sodium oxide and potassium oxide) which are usually present in lowamounts; and can also include titania and other minor oxides. Fiberdiameter is often in the range 3 to 20 microns, in particular 5 to 10microns, as conventional,

In one embodiment, the mineral fibers include glass fibers preferably inan amount up to 20%, more preferably up to 15% and most preferably up to10% of the total weight of starting materials. The remaining mineralfibers are preferably stone fibers. The glass fibers preferably have alength of from 10 mm to 50 mm, more preferably from 15 mm to 40 mm andmost preferably from 20 mm to 30 mm. These glass fibers serve toreinforce the composite.

Preferably, the mineral fibers, and aerogel particulate materialtogether form at least 60%, more preferably at least 65% and mostpreferably at least 70% of the total weight of starting materials.

Preferably, the mineral fibers, binder and aerogel particulate materialmake up at least 80%, more preferably at least 90% and most preferablysubstantially all of the total weight of starting materials.

In one embodiment, the fibers are provided in the form of a collectedweb and the method further comprises subjecting the collected web offibers to a disentanglement process. The disentangled fibers aresubsequently suspended in the primary air flow.

As used herein, the term “collected web” is intended to include anymineral fibers that have been collected together on a surface, i.e. theyare no longer entrained in air, e.g., granulate, tufts or recycled webwaste.

The collected web could be a primary web that has been formed bycollection of fibers on a conveyor belt and provided as a startingmaterial without having been cross-lapped or otherwise consolidated.Alternatively, the collected web could be a secondary web that has beenformed by cross-lapping or otherwise consolidating a primary web.Preferably, the collected web is a primary web.

A feeding mechanism may be provided for feeding in a web. The feedingmechanism may comprise a set of driven feed rollers. For example, theweb may be gripped between the feed rollers to be driven by the feedrollers for controlled advancing of the web to the disentanglementprocess.

In one embodiment, the disentanglement process comprises feeding the webof mineral fibers from a duct with a lower relative air flow to a ductwith a higher relative air flow. In this embodiment, the disentanglementis believed to occur, because the fibers that enter the duct with thehigher relative air flow first are dragged away from the subsequentfibers in the web. This type of disentanglement is particularlyeffective for producing open tufts of fibers, which can be penetrated bythe aerogel particulate material.

Preferably, the speed of the higher relative air flow is from 20 m/s to150 m/s or from 30 m/s to 120 m/s. More preferably, it is from 40 m/s to80 m/s and most preferably from 50 m/s to 70 m/s. The higher relativeair flow can be separate from the primary air flow, but more usually, itwill feed into the primary air-flow. Preferably, the difference in speedbetween the lower relative air flow and the higher relative air flow isat least 20 m/s, more preferably at least 40 m/s and most preferably atleast 50 m/s.

As used herein, the term “air flow” should be understood broadly so asto include not only a flow of air comprising gases in the proportionspresent in the atmosphere of Earth, but also a flow of any suitable gasor gases in any suitable proportions.

According to a particularly preferred embodiment, the disentanglementprocess comprises feeding the collected web to at least one roller whichrotates about its longitudinal axis and has spikes protruding from itscircumferential surface. In this embodiment, the rotating roller willusually also contribute at least in part to the higher relative airflow. Often, rotation of the roller is the sole source of the higherrelative air flow.

In some embodiments, there are at least two rollers. These rollers mayoperate in tandem or sequentially.

The roller may be of any suitable size, but in a preferred embodiment,the roller has a diameter based on the outermost points of the spikes offrom 20 cm to 80 cm or more preferably from 30 cm to 70 cm. Even morepreferably, the diameter is from 40 cm to 60 cm and most preferably from45 cm to 55 cm.

The roller may rotate at any suitable speed. For most embodiments, asuitable rate of rotation for the roller is from 500 rpm to 5000 rpm,preferably from 1000 rpm to 4000 rpm, more preferably from 1500 rpm to3500 rpm, most preferably from 2000 rpm to 3000 rpm.

The dimensions and rate of rotation of the roller can be selected toprovide a given speed at the circumference of the roller. In general, ahigh speed will result in a more effective disentanglement process,although this will depend on the type of web of mineral fibers used andthe exact form of the roller. In most embodiments, it will be suitablefor the outermost points of the spikes of the roller to move at a speedof from 20 m/s to 150 m/s, preferably from 30 m/s to 120 m/s, morepreferably from 40 m/s to 80 m/s and most preferably from 50 m/s to 70m/s.

The spikes may be permanently fixed to the roller for optimum resistanceto wear and tear. For example, the spikes may be fixed by gluing orwelding the spikes in blind holes arranged in the roller outerperiphery. Alternatively, the spikes may be replaceable. This can, forexample, be accomplished by the roller being a hollow cylinder withthrough holes in the cylindrical wall. The spikes can then, for example,have a head and be inserted through the holes from inside through theholes. Hereby, spikes can be replaced if they are broken or worn.Further, by having replaceable spikes, it is possible to change thepattern of the spikes. Hereby, it is possible to optimize the patternfor different types of material to be disentangled, e.g., loose mineralwool fibers, or a collected web of mineral wool fibers impregnated witha liquid binder.

The roller is preferably positioned within a substantially cylindricalchamber. The chamber will have an inlet duct through which the mineralfibers and optionally the aerogel particulate material and binder arefed to the roller. The chamber will also have an outlet through whichthe disentangled mineral fibers and optionally the aerogel particulatematerial and binder are expelled. Preferably, they are expelled in theprimary air flow through the outlet.

In preferred embodiments, the mineral fibers and optionally, the binderand aerogel particulate material are fed to the roller from above. It isalso preferred for the disentangled mineral fibers and optionally thebinder and aerogel particulate material to be thrown away from theroller laterally from the lower part of its circumference. In the mostpreferred embodiment, the mineral fibers are carried approximately 180degrees by the roller before being thrown off.

The roller preferably occupies the majority of the chamber. Preferablythe tips of the spikes are less than 10 cm, more preferably less than 7cm, and most preferably less than 4 cm from the curved wall of thesubstantially cylindrical chamber. This results in the air flow createdby the roller being greater and a more thorough disentanglement of thefibers by the air flow and by the spikes themselves.

Preferably, the mineral fibers are fed to the roller from above.

The disentangled fibers are generally thrown off the roller in theprimary air flow. In some embodiments, the roller will contribute to theprimary air flow. In other embodiments, the roller will be the solesource of the primary air flow.

The aerogel particulate material can be carried to the primary air flowin any suitable manner.

In one embodiment, a disentanglement process is used and the aerogelparticulate material is added to the collected mineral fiber web priorto the fiber disentanglement process and is suspended in the primary airflow together with the disentangled fibers. This method of addition ofthe aerogel particulate material generally promotes the most effectivemixing of the components. In this embodiment, the aerogel particulatematerial can be pre-mixed with the collected mineral fiber web andoptionally the binder in any suitable manner.

Alternatively, the aerogel particulate material can be carried to theprimary air flow suspended in a tributary air flow. The tributary airflow is combined with the primary air flow, thereby mixing the aerogelparticulate material with the fibers.

In some embodiments, it is not necessary to use a fiber disentanglementprocess. In one embodiment, the mineral fibers are provided as fibersentrained in air direct from a fiber-forming process. By this, it shouldbe understood that the fibers, having been entrained in air in theformation process (e.g. having been thrown from a spinner) are notcollected on a surface, but are transported as a suspension in air intothe primary air flow.

In this embodiment, the aerogel particulate material may be supplieddirect to the primary air flow, or carried to the primary air flowsuspended in a tributary air flow. The tributary air flow is combinedwith the primary air flow, thereby mixing the aerogel particulatematerial with the fibers.

Where a tributary air flow carries suspended aerogel particulatematerial to the primary air flow, the speed of the tributary air flow isgenerally lower than that of the primary air flow. Typically, thetributary air flow has a speed of from 1 to 20 m/s, preferably from 1 to13 m/s, more preferably from 2 to 9 m/s and most preferably from 3 to 7m/s.

According to the invention, the fibers and the aerogel particulatematerial are suspended in a primary air flow. This allows the componentsto mix intimately. An advantage of mixing as a suspension in an air flowis that unwanted particles or agglomerations can be sifted out. Suchparticles are, e.g., pearls of the fibers and agglomerations are interalia heavy chunks of wool, which have not been properly opened up tofibers, such as so-called chewing gum. In tests, mixing in an air flowperformed surprisingly well, as it was expected that the very differentphysical and aerodynamic properties of the particles and the fiberswould make this type of mixing impossible. It is remarkable thatsuperior mixing takes place in spite of the difference in density andshape of the particles and fibers. The density of the aerogel particlesis in the order of 140 kg/m³, whereas for example mineral wool fibershave a density in the order of 2,500 kg/m³. This might be expected tocause serious problems in the mixing process using an air flow, butsurprisingly does not.

The primary air flow is generally not free from turbulence. In preferredembodiments, there is significant turbulence within the primary air flowas this promotes mixing of the aerogel particulate material with themineral fibers. According to the present invention, the speed of theprimary air flow at its source is preferably from 20 m/s to 150 m/s,more preferably from 30 m/s to 120 m/s, even more preferably from 40 m/sto 80 m/s and most preferably from 50 m/s to 70 m/s.

The primary air flow is preferably a generally lateral air flow. Inembodiments where the aerogel particulate material is carried to theprimary air flow suspended in a tributary air flow, the primary air flowis preferably generally lateral and the tributary air flow is generallyupwards.

The primary air flow preferably enters a mixing chamber. In the mixingchamber, turbulence within the primary air flow allows more intimatemixing of the components.

In order to effect a thorough mixing of the fibers and particulatematerial, it is preferred to configure the apparatus such that theaverage dwell time of the aerogel particulate material and the fiberswithin the mixing chamber is at least 0.5 s, more preferably at least 2s, or even at least 3 s.

However, due to the effectiveness of mixing the aerogel particulatematerial and the fibers suspended in a gas, it is usually not necessaryfor the average dwell time of the particulate material and the fiberswithin the mixing chamber to be greater than 10 s. More usually, theaverage dwell time is less than 7 s and most usually the average dwelltime is less than 5 s.

The ambient temperature within the mixing chamber, when used, is usuallyfrom 20° C. to 100° C., more usually from 30° C. to 70° C. Thetemperature could be dependent on outside air temperature, i.e., cold inwinter and hot in summer. Elevated temperatures of up to 100° C. couldbe used for providing a pre-curing of the binder in the mixing chamber.

In specific embodiments, the binder is a material that, under certainconditions, dries, hardens or becomes cured. For convenience, these andsimilar such processes are referred to herein as “curing”. Preferably,these “curing” processes are irreversible and result in a cohesivecomposite material.

Inorganic, as well as, organic binders can be employed. Organic bindersare preferred. Further, dry binders, as well as, wet binders can beused. Specific examples of binder materials include but are not limitedto phenol formaldehyde binder, urea formaldehyde binder, phenol ureaformaldehyde binder, melamine formaldehyde binder, condensation resins,acrylates and other latex compositions, epoxy polymers, sodium silicate,hot melts of polyurethane, polyethylene, polypropylene andpolytetrafluoroethylene polymers etc.

In an embodiment, a dry binder is used. Any suitable dry binder could beused, but it is preferred to use a phenol formaldehyde binder, as thistype of binder is easily available and has proved efficient. It may bean advantage to use a dry binder as in some events mixing may be easy,and further the need for maintenance of the equipment is low. Further,the binder is relatively stable and storable.

According to an alternative embodiment, a wet binder is used. Wetbinders have the advantage of low cost compared to dry binders, and itis often possible to reduce the amount of binder using wet bindercompared to dry binders. A reduction in the amount of binder furtherresults in a better reaction of the composite to fire. Any suitable wetbinder could be used, but it is preferred to use a phenol formaldehydebinder, as this type of binder is easily available and has provedefficient.

The binder may be mixed with the mineral fibers and/or aerogelparticulate material before, during or after mixing of the mineralfibers with the aerogel particulate material. In some embodiments,especially where the binder is wet, it is preferred to mix the binderwith the fibers prior to the mixing of the fibers with the aerogelparticulate material. In particular, the fibers can be in the form of anuncured collected web containing wet binder.

Alternatively, wet binder could be sprayed onto fibers entrained in airas they are carried to the primary air flow direct from a fiber-formingprocess.

When dry binder is used, this could, for example, be pre-mixed with acollected web of mineral fibers and optionally aerogel particulatematerial. Alternatively, it could be supplied to the primary air flowseparately and mixed in the primary air flow.

The mineral fibers, binder and aerogel particulate material, whensuspended in the primary air flow, are in some embodiments, subjected toa further air flow in a different direction to the primary air flow.This helps to generate further turbulence in the primary air flow, whichassists mixing further. Usually the primary air flow is generallylateral and the further air flow is generally upwards. In someembodiments, a plurality of further air flows is provided.

Preferably, the further air flow has a speed of from 1 to 20 m/s, morepreferably from 1 to 13 m/s, even more preferably from 2 to 9 m/s andmost preferably from 3 to 7 m/s.

The mixture of mineral fibers, aerogel particulate material and binderis collected from the primary air flow by any suitable means. In oneembodiment, the primary air flow is directed into the top of a cyclonechamber, which is open at its lower end and the mixture is collectedfrom the lower end of the cyclone chamber.

In an alternative embodiment, the primary air flow is directed through aforaminous surface, which catches the mixture as the air flow passesthrough.

In embodiments where there is a disentanglement process before thefibers are suspended in the primary air flow, the mixture of mineralfibers, aerogel particulate material and binder is preferably subjectedto a further fiber disentanglement process after the mixture has beensuspended in the primary air flow, but before the mixture is pressed andcured.

The further disentanglement process may have any of the preferredfeatures of the disentanglement process described previously.

In a particularly preferred method, the mixture of mineral fibers,binder and aerogel particulate material is removed from the primary airflow, preferably in a cyclone chamber, and fed to a rotating rollerhaving spikes protruding from its circumferential surface. The roller ofthe further disentanglement means may have any of the features describedabove in relation to the roller to which the collected web can be fedinitially.

The mixture of mineral fibers, aerogel particulate material and binderis preferably thrown from the further disentanglement process into aforming chamber.

Raving undergone the further disentanglement process, the mixture ofmineral fibers, aerogel particulate material and binder is collected,pressed and cured. Preferably, the mixture is collected on a foraminousconveyor belt having suction means positioned below it.

In a preferred method, according to the invention, the mixture ofaerogel particulate material, binder and mineral fibers, having beencollected, is scalped before being cured and pressed.

The method may be performed as a batch process, however according to anembodiment, the method is performed at a mineral wool production linefeeding a primary or secondary mineral wool web into the fiberseparating process, which provides a particularly cost efficient andversatile method to provide composites having favorable mechanicalproperties and thermal insulation properties in a wide range ofdensities.

According to a special embodiment, the method is performed as an on-lineprocess in a mineral wool production line.

Once the mixture of mineral fibers, aerogel particulate material andbinder has been collected, it is pressed and cured to produce acomposite of the desired density.

Pressure, temperature and holding time for the curing and pressing isdependent inter alia on the type of binder used. Examples oftemperatures and holding times used in preliminary tests are mentionedbelow.

An aspect of the invention relates to an aerogel-containing compositeobtainable by the method of the invention.

A further aspect of the invention relates to an aerogel-containingcomposite comprising fibers in an amount of from 24 to 80 wt % of thetotal weight of starting materials, aerogel particulate material in anamount of from 10 to 75 wt % of the total weight of starting materials,binder in an amount of from 1 to 30 wt % of the total weight of startingmaterials, wherein the composite is substantially homogeneous and iscured and pressed to a density between 120 kg/m³ and 800 kg/m³, such asbetween 150 kg/m³ and 800 kg/m³.

By the wording “substantially homogeneous”, it should be understood thatthe composite is homogeneous at a millimeter scale, i.e., a microscopeimage of a given area on a millimeter scale is (substantially) identicalto other samples of the mixture. It further means that after mixing, thematerials are distributed substantially evenly within the composite,i.e., that the aerogel particulates are present in substantially thesame amount in the whole composite.

Preferably, the millimeter scale area is 1 mm². However, if thecomposite contains discrete particles in the order of 100 μm and above,“substantially homogeneous” can be defined in relation to the largestdiscrete ingredient. Hence, it should be understood that the compositeis visually homogeneous at a scale related to the largest discreteingredient, e.g., 10 times the size of the largest particulate. For aparticle size of say 1 mm (largest dimension) a visual investigation ofan area of, e.g., 100 mm² is (substantially) identical to other samplesof the mixture. It further means that after mixing, the materials aredistributed substantially evenly within the composite, i.e., that theaerogel particulates are present in substantially the same amount in thewhole composite with no visual accumulations.

Any of the preferred features of the final product described in relationto the method apply equally to the composite of the invention whererelevant.

The invention also relates to novel apparatuses suitable for carryingout the method of the invention.

A first novel apparatus comprises:

a mineral fiber-forming apparatus for producing a supply of fibersentrained in air,

binder supply apparatus for supplying binder to the fibers,

a first collector arranged to receive the fibers from the fiber-formingapparatus, suction apparatus for applying suction through the collectorand thereby collecting the fibers on the collector as a web,

a disentanglement apparatus for disentangling the web to providedisentangled fibers,

web supply apparatus for supplying the web to the disentanglementapparatus, aerogel particulate material supply apparatus positionedbefore or after the disentanglement apparatus,

air supply apparatus for supplying a primary air flow in which tosuspend disentangled mineral fibers,

a second collector for collecting the disentangled mineral fibers,binder and aerogel particulate material,

a press for pressing the collected mineral fibers, binder and aerogelparticulate material.

The mineral fiber-forming apparatus can be any apparatus suitable forthat purpose, for example, a cascade spinner or a spinning cup. Inpreferred embodiments of the apparatus, the mineral fiber-formingapparatus is a cascade spinner. In each case, a mineral melt is suppliedand fibers are produced by the effect of centrifugal action of theapparatus.

The binder supply means supplies binder to the mineral fibers. It can bepositioned at any point before the second collector, but is preferablypositioned between the fiber-forming apparatus and the first collector.In another embodiment, the binder supply means is positioned between thefirst collector and the second collector. In another preferredembodiment, the binder supply means is positioned between the firstcollector and the disentanglement means.

The binder supply means could be adapted to supply wet binder or tosupply dry binder.

The first collector is preferably in the form of a continuously operatedfirst conveyor belt. The belt is pervious to air. The fibers form aprimary web on the belt. Suction means are positioned behind the firstcollector to allow an air flow through the collector.

The first apparatus may optionally comprise means for treating theprimary web in any manner known to the person skilled in the art. Forexample, the apparatus can comprise a pendulum belt for cross-lappingthe primary web onto a further continuously operated conveyor belt, toform a secondary mineral fiber web.

In a preferred embodiment, the first collector is in the form of aconveyor belt leading to an inlet duct. The inlet may have conveyingrollers at its upper edge to assist with the movement of the mineralfibers through the inlet duct.

Between the first collector and the disentanglement apparatus, in someembodiments, there is a substantially vertical duct. Often thesubstantially vertical duct will be narrower at its lower end than atits upper end.

The first apparatus comprises disentanglement means for disentanglingthe primary or secondary web to form disentangled fibers. In oneembodiment, the disentanglement apparatus has a first duct for carryingthe primary or secondary web and a second duct adjoined to the firstduct. In this embodiment, the disentanglement apparatus comprises meansfor supplying an air flow in the second duct with a higher speed than ispresent in the first duct.

In particular, the disentanglement means can be in the form of a rolleras described in relation to the method of the invention. Any of thepreferred or optional features of the roller described in relation tothe method are equally applicable to the first novel apparatus of theinvention.

Furthermore, the first apparatus can comprise a cylindrical chamber thathouses the roller. Any of the features of the cylindrical chamber thatare described in relation to the method of the invention are equallyapplicable in relation to the first apparatus of the invention.

The first apparatus of the invention also requires air supply means forsupplying the primary air flow. This air supply means can be formed aspart of the disentanglement apparatus. For example, the means forsupplying an air flow in the second duct with a higher speed than ispresent in the first duct could also be the supply of the primary airflow.

It is also possible for the roller to act as the means for generatingthe primary air flow itself as it creates a flow of disentangled mineralfibers suspended in an air flow.

A second novel apparatus comprises:

a mineral fiber-forming apparatus for producing a supply of fiberssuspended in a primary air flow,

air supply apparatus for supplying the primary air flow,

binder supply apparatus for supplying binder to the fibers,

aerogel particulate material supply apparatus for supplying aerogelparticulate material to the primary air flow,

a collector for collecting the mineral fibers, binder and aerogelparticulate material,

a press for pressing the collected mineral fibers, binder and aerogelparticulate material.

The mineral fiber-forming apparatus of the second apparatus of theinvention can also be any apparatus suitable for that purpose, forexample, a cascade spinner or a spinning cup. In preferred embodimentsof the apparatus, the mineral fiber-forming apparatus is a cascadespinner.

In the second apparatus of the invention, air supply means are requiredfor supplying the primary air flow. This can be in the form of a supplyof cooling gas directed axially to the rotating wheels of a cascadespinner, in which fibers are carried from the spinner having been thrownoff the wheel.

Binder supply means are positioned to supply binder, usually in the formof a spray to the fibers suspended in an air flow.

In both apparatuses of the invention, aerogel particulate materialsupply means are required. The aerogel particulate material supply meansmay comprise a hopper containing aerogel particulate material. Dosedsupply of aerogel particulate material may be obtained by a screwfeeder, weighing cell or any suitable means for precise dosing ofparticulate material.

In the first apparatus, although the aerogel particulate material musteventually be supplied to the primary air flow, it is not necessary thatit is supplied from the supply means direct to the air flow. In fact, itis preferred to position the aerogel particulate material supply meansto supply aerogel particulate material to the web of mineral fibers andfeed these together to the disentanglement apparatus. Where it ispositioned before the disentanglement means, the aerogel particulatematerial is supplied to the primary air flow together with thedisentangled fibers.

However, the aerogel particulate material could also be positioned afterthe disentanglement means.

In the second apparatus and optionally in the first apparatus, theaerogel particulate material supply means is positioned to supplyaerogel particulate material to the primary air flow. Optionally, atributary air flow supply means can be positioned to supply a tributaryair flow for carrying the aerogel particulate material to the primaryair flow.

In both apparatuses, a further air flow supply means may be present forsupplying a further air flow to the primary air flow.

Each of the apparatuses of the invention preferably comprises a mixingchamber as described in relation to the method of the invention. Thetributary and/or further air flow supply means, when present, arepreferably positioned at the lower end of the mixing chamber andconfigured to supply an upwards flow of air within the mixing chamber.The primary air flow supply means is preferably positioned at the sideof the mixing chamber and is configured to supply an air flow laterallyacross the chamber.

When present, the further air flow supply means may have a gauzedisposed across its opening to prevent the entry of solid materials.

At the lower end of the mixing chamber, there is preferably a dischargeopening into which heavy pellets or compacted fibers fall.

In preferred embodiments, the mineral fibers, aerogel particulatematerial and binder enter the mixing chamber together at one sidesuspended in the primary air flow. The mixture is then blown upwards andfurther mixed by a further air supply means positioned at the lower endof the chamber. The mixture then leaves the mixing chamber via a removalduct at the upper end of the mixing chamber.

The removal duct leads eventually to a collector. In the first apparatusof the invention, this is the second collector. The collector may be inthe form of a foraminous belt, behind which suction means arepositioned.

Alternatively, the collection means could comprise a cyclone chambercapable of separating the mixture of mineral fibers, binder and aerogelparticulate material from the primary air flow. In this embodiment, thecyclone chamber has an opening at its lower end, through which themixture is ejected, whilst the air flow is removed through a duct at theupper end. The cyclone chamber has a greater diameter at its upper endthan at its lower end.

In one embodiment the mixture is ejected from the cyclone chamber onto aconveyor belt.

In the first apparatus of the invention, there is preferably a furtherdisentanglement apparatus positioned to receive the mixture of mineralfibers, aerogel particulate material and binder. The furtherdisentanglement apparatus may have any of the preferred featuresdescribed in relation to the disentanglement apparatus for disentanglingthe collected web of mineral fibers.

Preferably, the further disentanglement apparatus is positioned toreceive the mixture of mineral fibers, aerogel particulate material andbinder from the opening at the lower end of the cyclone chamber.

Preferably, there is a forming chamber positioned to receive fibers fromthe further disentanglement apparatus. Preferably, the forming chambercomprises a foraminous conveyor belt for collecting the mixture ofmineral fibers, aerogel particulate material.

In each of the apparatuses of the invention, it is preferred to providescalping means prior to the press. The apparatus can be configured torecycle the scalped material.

Each of the apparatuses according to the present invention comprises apress for pressing and curing the collected mixture of mineral fibers,binder and aerogel particulate material. The press is suitable forpressing the composite to a density of from 120 kg/m³ to 800 kg/m³, inparticular from 150 kg/m³ to 800 kg/m³. Generally, the press is adaptedto heat the composite in order to cure the binder.

Any of the preferred features described in relation to the method of theinvention apply equally in relation to the apparatus. Similarly, any ofthe apparatus features disclosed above apply equally in relation to themethod of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in the following by way of example andwith reference to the drawings in which:

FIG. 1 is a schematic drawing of an apparatus for fiber separating andmixing raw materials;

FIG. 2 is a schematic drawing of a further disentanglement apparatus asdescribed above;

FIG. 3 is a photo of a composite panel according to the invention madein a pilot run;

FIG. 4 is a microscope photo of a sample of an aerogel-containingcomposite according to the invention;

FIG. 5 is a microscope photo of a sample of an aerogel-containingcomposite according to the invention;

FIG. 6 is a microscope photo of a sample of an aerogel-containingcomposite according to the invention;

FIG. 7 is a photograph of a composite manufactured using a mixing methodother than that according to the invention; and

FIG. 8 is a photograph of further composites manufactured using a mixingmethod other than that according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

Apparatus suitable for use in the method of the present invention can beseen in FIG. 1. Where a fiber-forming apparatus and collector areconfigured to carry a mineral fiber web to the inlet duct 1, a bindersupply means is positioned to supply binder to the mineral fibers and anaerogel particulate supply means is positioned to supply aerogelparticulate material to the inlet duct, the apparatus shown could alsoform part of the first novel apparatus of the invention.

The apparatus comprises an inlet duct 1 for starting materials, e.g.,aerogel particles, binder and mineral fibers and for specific rawmaterials the apparatus may comprise a shredder (not shown) at the inletduct 1 to at least partly cut up bulky material. At the lower edge ofthe inlet duct, there is a conveyor 2 that carries the raw materialsthrough the inlet duct 1. At the upper edge of the inlet duct, conveyingrollers 3 assist with feeding the starting materials through the inletduct 1. At the end of the inlet duct 1, a first set of mutually spacedelongate elements 4 extend across the end of the inlet duct 1. Theseserve to break up larger pieces of the starting materials, for examplethe mineral fiber web. In some embodiments, the elongate elements 4 arein the form of rotating brushes that draw the starting materials betweenthem as they rotate.

The starting materials that pass through the end of the inlet then falldownwards into a substantially vertical duct 5. In the embodiment shown,a second set of mutually spaced elongate elements 6 extend across theupper end of the duct. The second set of elongate element is usuallymore closely spaced than the first. In the embodiment shown, the secondset of elongate elements rotate so as to allow sufficiently small piecesof the mineral fiber web to pass through, but carry larger pieces awayvia a starting material recycling duct 7.

The vertical duct 5 generally becomes narrower at its lower end. In theembodiment shown, the lower end of the vertical duct forms the inlet 8to the substantially cylindrical chamber 9. As shown, the inlet 8 is atan upper part of the substantially cylindrical chamber 9. In use,starting materials pass through the vertical duct 5 and through theinlet 8 into the cylindrical chamber 9.

The cylindrical chamber 9 houses a roller 10 having spikes 11 protrudingfrom its circumferential surface 12. The roller 10 shown in FIG. 1rotates anticlockwise as shown in the drawing, so that startingmaterials are carried from the inlet (8) around the left side of theroller 10 as shown and thrown out laterally in a primary air flow into amixing chamber 14. The cylindrical chamber 9 and the roller 10 togetherform the disentanglement means. The disentanglement means causedisentanglement of the fibers, meaning that the fibers, which may beprovided as wool entangled as a web or as tufts, will be worked on toprovide more open wool or even loose fibers, thereby facilitatingsubsequent mixing of the fibers with other components.

In the embodiment shown, the primary air flow is created by the rotationof the roller 10 within the cylindrical chamber 9, and in particular bythe movement of the spikes 11 and starting material through the spacebetween the circumferential surface of the roller and the curved wall 13of the cylindrical chamber 9.

The mixing chamber 14 shown in FIG. 1 comprises a discharge opening 16and further air flow supply means 15. The further air flow supply means15 comprise openings through which the further air flow is supplied.Gauzes 17 are disposed across the openings of the further air flowsupply means 15. These gauzes allow the further air flow to pass throughinto the mixing chamber 14, but are intended to prevent the entry ofmaterials into the supply means. The further air flow supply means 15direct the further air flow upwards into the mixing chamber 14.

The further air flow meets the primary air flow containing thedisentangled fibers in the mixing chamber. The further air flow has theeffect of carrying the mixture of disentangled fibers, binder andaerogel particulate material upwards within the mixing chamber 14. Somemore compacted fibers and pearls of mineral material will not be carriedupwards in the mixing chamber, but fall to the lower end and through thedischarge opening 16.

The desired mixture of disentangled fibers, aerogel particulate materialand binder is carried to the upper part of the mixing chamber 14 where aremoval duct 18 is positioned to carry the mixture from the mixingchamber 14. A first air recycling duct 19 is adjoined to the removalduct 18 and recycles some of the air from the removal duct 18 back tothe further air supply means 15.

The removal duct leads to a cyclone chamber 20. The cyclone chamber 20has a second air recycling duct 22 leading from its upper end to thefurther air supply means 15. A filter 21 is adjoined to the second airrecycling duct. In use, the filter 21 removes any stray mineral fibers,aerogel particulate material and binder from the second air recyclingduct 22. As air is removed from the upper end of the cyclone chamber 20,the mixture of disentangled fibers, aerogel particulate material andbinder falls through a cyclone chamber outlet 23 at the lower end of thecyclone chamber 20.

A collector 24 is positioned below the cyclone chamber outlet 23. In theembodiment shown, the collector 24 is in the form of a conveyor, whichcarries the collected fibers to a pressing and curing apparatus (notshown).

FIG. 2 shows an embodiment of the further disentanglement apparatus,which may optionally be used in the method. The further disentanglementapparatus can be positioned in place of collector 24 as shown in FIG. 1.The further disentanglement apparatus shown comprises roller 25, whichis the same as roller 10 in structure. The mixture of components is fedto roller 25 from above and thrown out into forming chamber 26. At itslower end, the forming chamber 26 comprises a foraminous conveyor belt27, below which suction means 28 are positioned. Scalper 29 ispositioned to scalp the top of the mixture to provide an even surface.The scalped material can then be recycled.

Foraminous conveyor belt 27 carries the mixture to a press (not shown).

The photo in FIG. 3 depicts a composite panel produced in a pilot run ona full-scale apparatus according to the invention. The composite rawmaterials fed into the apparatus were uncured stone wool web with wetbinder and aerogel particulates. The sample shown is approximately 20cm×20 cm. The composite panel is seen to be very homogeneous. It is notpossible to see the aerogel particles with the naked eye. The stone woolweb was disintegrated and opened up in the apparatus, and there are onlysmall fiber tufts visible on the surface, and there is a random patternof the small fiber tufts, so there is no indication of accumulation orvariation in distribution.

The microscope photo of FIG. 4 shows a sample of an aerogel-containingcomposite made according to the invention using loose stone wool fibers.The aerogel particulate material can be seen as small dots or grains.The fibers are also visible. As can be seen, the aerogel particulatematerial and fibers are substantially homogeneously mixed on a 1 mmscale.

The microscope photograph of FIG. 5 shows the mixture of aerogelparticles and fibers in the panel according to the invention. The twolargest particles are measured to 481 μm and 302 μm. The composition ofthe analyzed panel was approximately 51 wt % aerogel particles, 38 wt %mineral wool fibers and 11 wt % binder.

Similarly, the microscope photograph of FIG. 6 shows the mixture ofaerogel particles and fibers in the panel according to the invention inlarger magnification. There is no sign that the binder attaches to theaerogel particles. This is considered highly beneficial as mentionedabove.

In the testing, a dry phenol formaldehyde polymer binder (powder) wasused of the type sold by Dynea under the trade name “Prefere 94 8182U7”.Binder content in the test was 12%-wt to be sure that the boardsproduced had sufficient strength. Curing time in initial tests startedat 7 minutes, and was subsequently raised to 14 minutes to be sure ofproper curing.

FIGS. 7 and 8 are comparative examples showing composites not producedaccording to the invention.

FIG. 7 is a photograph showing the result achieved when the componentsof the composite are mixed by a method not according to the presentinvention. In this case, the components were mixed with a blender. It isclear from FIG. 7 that the composite is not homogeneous, because compactballs of fibers and separated regions of aerogel, fibers and binder arevisible with the naked eye. This is in contrast to the smooth andhomogeneous appearance of composites manufactured according to theinvention, in particular as shown in FIG. 3.

Similarly, FIG. 8 is a photograph of a number of composites comprising10-31% aerogel particulate material, mineral fibers and approximately10% dry binder. The components of the composite were mixed in a blenderusing a method not according to the invention. Again, compacted balls offibers and distinct regions of the different components can be seen inthe composites, which is in contrast to the homogeneous appearance ofcomposites manufactured according to the invention, in particular asshown in FIG. 3.

In tests, aerogel particulate material of the type “Nanogel® FineParticle Aerogel” from Cabot International was used and showed excellentresults.

The tests were carried out with stone wool fibers having a density ofapproximately 2,800 kg/m³.

The requirement for the composite of being substantially homogeneous is,in this case, considered fulfilled with a maximum variation of 5% (e.g.density) in an X-Y plane co-planar with the major surfaces of thecomposite panel. A higher variation is accepted in the Z-plane, i.e.,the thickness of the composite panel.

The invention claimed is:
 1. A method for manufacturing anaerogel-containing composite, said method comprising the steps of:providing mineral fibers in an amount of from 24 to 80 wt % of the totalweight of starting materials, wherein the mineral fibers are provided inthe form of a collected web and the collected web of fibers are furthersubjected to a disentanglement process, providing an aerogel particulatematerial in an amount of from 10 to 75 wt % of the total weight ofstarting materials, providing a binder in an amount of from 1 to 30 wt %of the total weight of starting materials, suspending the mineral fibersin a primary air flow and suspending the aerogel particulate material inthe primary air flow, thereby mixing the suspended aerogel particulatematerial with the suspended mineral fibers, and mixing the binder withthe mineral fibers and/or aerogel particulate material before, during orafter mixing of the mineral fibers with the aerogel particulatematerial, collecting the mixture of mineral fibers, aerogel particulatematerial and binder and pressing and curing the mixture to provide aconsolidated composite with a density of from 120 kg/m³ to 800 kg/m³;wherein the mineral fibers, binder and aerogel particulate material,when suspended in the primary air flow, are subjected to a further airflow in a different direction to the primary air flow; wherein theprimary air flow is generally lateral and the further air flow isgenerally upwards.
 2. A method according to claim 1, wherein thedisentanglement process comprises feeding the web from a duct with alower relative air flow to a duct with a higher relative air flow.
 3. Amethod according to claim 2, wherein the speed of the higher relativeair flow is from 20 m/s to 150 m/s.
 4. A method according to claim 1,wherein the disentanglement process comprises feeding the collected webto at least one roller which rotates about its longitudinal axis and hasspikes protruding from its circumferential surface.
 5. A methodaccording to claim 4, wherein the roller has a diameter based on theoutermost points of the spikes of from 20 cm to 80 cm.
 6. A methodaccording to claim 4, wherein the roller rotates at a rate of from 500rpm to 5000 rpm.
 7. A method according to claim 4, wherein the outermostpoints of the spikes of the roller move at a speed of from 20 m/s to 150m/s.
 8. A method according to claim 1, wherein the aerogel particulatematerial is added to the collected mineral fiber web prior to the fiberdisentanglement process and is suspended in the primary air flowtogether with the disentangled fibers.
 9. A method according to claim 1,wherein the mineral fibers are in the form of an uncured web containingwet binder.
 10. A method according to claim 1, wherein the method isperformed at a mineral wool production line, which feeds a primary orsecondary mineral wool web into the fiber disentanglement process.
 11. Amethod according to claim 1, wherein the mixture of mineral fibers,aerogel particulate material and binder is subjected to a further fiberdisentanglement process after the mixture has been suspended in theprimary air flow, but before the mixture is pressed and cured.
 12. Amethod according to claim 1, wherein the mineral fibers are provided asfibers entrained in air direct from a fiber-forming process.
 13. Amethod according to claim 1, wherein at least part of the aerogelparticulate material is carried to the primary air flow as aerogelparticulate material suspended in a tributary air flow and the methodcomprises combining the tributary air flow with the primary air flow andthereby mixing the aerogel particulate material with the mineral fibers.14. A method according to claim 1, wherein the mineral fibers, binderand aerogel particulate material, when suspended in the primary airflow, are subjected to a further air flow in a different direction tothe primary air flow.
 15. A method according to claim 14, wherein theprimary air flow is generally lateral and the further air flow isgenerally upwards.
 16. A method according to claim 1, wherein theprimary air flow has an initial speed of from 20 m/s to 150 m/s.
 17. Amethod according to claim 14, wherein the further air flow has a speedof from 1 to 20 m/s.
 18. A method according to claim 1, wherein thebinder is provided in dry form.
 19. A method according to claim 1,wherein the binder is provided in wet form.